[leetcode]463. Island Perimeter

[leetcode]463. Island Perimeter

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Analysis

ummmm~—— [ummmm~]

You are given a map in form of a two-dimensional integer grid where 1 represents land and 0 represents water. Grid cells are connected horizontally/vertically (not diagonally). The grid is completely surrounded by water, and there is exactly one island (i.e., one or more connected land cells). The island doesn’t have “lakes” (water inside that isn’t connected to the water around the island). One cell is a square with side length 1. The grid is rectangular, width and height don’t exceed 100. Determine the perimeter of the island.
直接遍历，当一个网格为1时，看他的上下左右是否为0，如果为0周长加一，当然注意要注意一下边界~

Implement

class Solution {
public:
    int islandPerimeter(vector<vector<int>>& grid) {
        int res = 0;
        int n = grid.size();
        int m = grid[0].size();
        for(int i=0; i<n; i++){
            for(int j=0; j<m; j++){
                if(grid[i][j] == 1){
                    if(i==0 || grid[i-1][j]==0)
                        res++;
                    if(i==n-1 || grid[i+1][j]==0)
                        res++;
                    if(j==0 || grid[i][j-1]==0)
                        res++;
                    if(j==m-1 || grid[i][j+1]==0)
                        res++;
                }
            }
        }
        return res;
    }
};